As some adults this week rifle through plastic grass in the hopes of finding a stray chocolate egg left over from Easter, they can take some solace that chocolate may be good for them–at least in small quantities and preferably if it's dark chocolate, according to researchers in Germany. In a study published online in the European Heart Journal, they report that one small square of chocolate a day can lower blood pressure and reduce the risk of heart disease.

 

Researchers in Germany followed 19,357 people, aged between 35 and 65, for at least ten years and found that those who ate the most amount of chocolate—an average of 7.5 grams a day—had lower blood pressure and a 39 percent lower risk of having a heart attack or stroke compared to those who ate the least amount of chocolate—an average of 1.7 grams a day. The difference between the two groups amounts to six grams of chocolate: the equivalent of less than one small square of a 100g bar.

 

To put it in terms of absolute risk, the reserachers say the data suggest that if people in the group eating the least amount of chocolate (of whom 219 per 10,000 had a heart attack or stroke) increased their chocolate intake by six grams a day, 85 fewer heart attacks and strokes per 10,000 people could be expected to occur over a period of about 10 years. If the 39 percent lower risk is generalized to the general population, the number of avoidable heart attacks and strokes could be higher because the absolute risk in the general population is higher.

 

However, Brian Buijsse, a nutritional epidemiologist at the German Institute of Human Nutrition, in Nuthetal, Germany, who led the study, warned that it was important people ensured that eating chocolate did not increase their overall intake of calories or reduce their consumption of healthy foods. “Small amounts of chocolate may help to prevent heart disease, but only if it replaces other energy-dense food, such as snacks, in order to keep body weight stable,” he says.

 

"Our hypothesis was that because chocolate appears to have a pronounced effect on blood pressure, therefore chocolate consumption would lower the risk of strokes and heart attacks, with a stronger effect being seen for stroke," explained Dr Buijsse.

This is, in fact, what the study found. During the eight years there were 166 heart attacks (24 fatal) and 136 strokes (12 fatal); people in the top quartile had a 27% reduced risk of heart attacks and nearly half the risk (48%) of strokes, compared with those in the lowest quartile.

 

The researchers found lower blood pressure due to chocolate consumption at the start of the study explained 12 percent of the reduced risk of heart attacks and strokes, but even after taking this into account, those in the top quartile still had their risk reduced by a third (32 percent) compared to those in the bottom quartile over the duration of the study.

Although more research needs to be carried out, the researchers believe that flavanols in cocoa may be the reason why chocolate seems to be good for people's blood pressure and heart health. And since there is more cocoa in dark chocolate, dark chocolate may have a greater effect.

 

“Flavanols appear to be the substances in cocoa that are responsible for improving the bioavailability of nitric oxide from the cells that line the inner wall of blood vessels–vascular endothelial cells,” said Buijsse. “Nitric oxide is a gas that, once released, causes the smooth muscle cells of the blood vessels to relax and widen. This may contribute to lower blood pressure. Nitric oxide also improves platelet function, making the blood less sticky, and makes the vascular endothelium less attractive for white blood cells to attach and stick around."

 

While the authors of the study say the health effecs of cocoa are promising and chocolate may become part of a diet that aims to prevent cardiovascular disease if other studies confirm their findings, a 100g bar of chocolate has about 500 calories. Anyone embracing chocolate to combat heart disease might want to be sure they cut an equivalent amount of calories from their diet to avoid weight gain, the reserachers say.